Abstract

This thesis is concerned with understanding and directing the
functionalisation of solid surfaces with materials: molecules, nanoparticles and
crystals. Both conducting (electrode) and insulating surfaces are of interest. For
molecular functionalisation, a sweep potential procedure has been developed to
assist the formation of self assembled monolayers (SAMs) of a ruthenium
thiolated complex. Electrochemical investigations were employed to
characterised the SAM formed on a platinum electrode.
Nanoparticles formation explored two distinct routes. First Pd
nanoparticles were successfully formed within ultra-thin Nafion films via
impregnation and a chemical reduction method. Morphological investigations
utilised atomic force microscopy. The electrocatalytic properties of the
nanocomposite material were elucidated for the hydrogen oxidation reaction. The
methodology used for the preparation of this nanocomposite material shows
promise for applications in sensors and fuel cells. Second, the potential-assisted
deposition of pre–formed perthiolated-ß-cyclodextrin-capped Pt nanoparticles
method is described. Pt nanoparticles (5 nm diameter) were deposited in a
controlled fashion on indium tin oxide and highly oriented pyrolytic graphite
electrodes. The Pt nanoparticles formed in this way were electrocatalytically
active towards hydrogen generation and oxidation. This new approach for the
deposition of metal nanoparticles with controlled surface density provides a new
tool for the investigation of electrocatalytic processes.
A major focus of the second part of the thesis has been the development
of methods to study crystal deposition at extreme supersaturation. For this
purpose a delivery system for calcium carbonate at high-supersaturation ion has
been coupled with a quartz crystal microbalance and in–situ optical microscopy.
The dynamics and quantitative evaluation of calcium carbonate deposition onto
foreign solid substrates, and the effect of various additives, are described. Ex–
situ studies, scanning electron microscopy and microRaman spectroscopy,
allowed the morphological characterisation of the phases deposited. The
transformation of ACC to calcite has been explored in details. In the study of
additives, a significant finding was that citrate concentration shows a nonmonotonic
behaviour on the amount of scale deposited. Fast screening of
different additives (polymeric and molecular) and a quantitative ranking of their
inhibitory properties on calcium carbonate deposition on a gold surface is
described. Molecular and polymeric additives showed different inhibitory
mechanisms on the scaling process and the technique employed gave a better
insight into their mode of action.